Just hours after photographing the Transit of Venus, I took another photo that became one of this year's favorites. This photo shows the expansive interior of one of the world's most historic buildings - the "Hagia Sophia", in Istanbul, Turkey. Completed in 537 AD, this was the largest Christian cathedral in the world for almost 1000 years. After the Ottoman conquest of Constantinople in 1453, it became a mosque. It is now a museum.